Borrelia sp. are tick-borne microacrophilic spirochetes that cause relapsing fever and Lyme disease/Lyme arthritis in humans. Very little is known about the physiology of these organisms, primarily due to the difficulty of cultivating these organisms on artificial medium. Basic investigations into the fermentation pathways, oxygen utilization (if any), and how oxygen is toxic to these organisms have not been carried out because of the very fastidious nature of Borrelia. This investigator has successfully cultivated three species of Borrelia in large batch cultures and under a variety of conditions. The proposed research will lead to a better understanding of the physiology and microaerophilic nature of Borrelia sp. The general approach will be to study the effect of adding compounds known to scavenge oxygen products to the medium on the growth of these organisms. Also oxygen radicals, such as superoxide and hydroxyl radicals, will be generated in the medium and their effect on cell survival observed. The presence of enzymes which serve to protect cells from oxygen products will be determined by specific assay. Localization of enzyme activity and the presence of isozymes will be determined by one- and two-dimensional polyacrylamide gel electrophoresis. Oxygen utilization will be determined by measuring oxygen uptake with an oxygen electrode and detection of cytochromes. This data will be particularly useful in understanding how Borrelia has adapted itself as a parasite and lead to further information on the organism's ability to cause disease.